(a) Field
The disclosure herein relates to a method for generating a virtual engine sound and to a virtual engine sound generating system using the same. More particularly, the disclosure relates to a method for generating a virtual engine sound which is time synchronized with a waveform of an actual engine sound and is robust to an environmental change; and a virtual engine sound generating system using the same.
(b) Description of the Related Art
In order to change the tone of an actual engine sound which is generated as an engine is operated, an ASD (Active Sound Design) method is under research. By overlapping the virtual engine sound on the actual engine sound, a sensory quality related to the engine sound may be improved.
A related art process for generating the virtual engine sound will be described, with reference to FIG. 3.
FIG. 3 illustrates a graph for describing a related art process for generating the virtual engine sound.
Referring to FIG. 3, a controller has an actual engine sound line which varies with an engine RPM stored therein. The actual engine sound line varied with the engine RPM may be set in advance with an experiment taking a specification of the engine into account. The controller has a target engine sound line in which sound volume increases according to the engine RPM stored therein. The target engine sound line may be preset to a value a person of an ordinary skill in the art may determine to be desirable. Alternatively, the target engine sound line may be set to a value the user desires. The controller determines the sound volume of the virtual engine sound matched to the virtual engine sound line for generating the same.
However, in a particular engine RPM state, if the waveform of the actual engine sound having a frequency at the particular engine RPM is not time synchronized with the waveform of the virtual engine sound having that frequency, a problem may be caused, in which the sound volume matched to the target engine sound line fails to output due to destructive interference and constructive interference.
Moreover, the sound volume of the actual engine sound varies with environmental changes, such as temperature, duration of use and degradation of the vehicle. However, since the actual engine sound line is preset by experiment at room temperature (For an example, 20° C.), a problem may be caused, in which the sound volume matched to the target engine sound line fails to output.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.